8f7dc9ae4a
Using l2tp_tunnel_find() in l2tp_ip_recv() is wrong for two reasons:
* It doesn't take a reference on the returned tunnel, which makes the
call racy wrt. concurrent tunnel deletion.
* The lookup is only based on the tunnel identifier, so it can return
a tunnel that doesn't match the packet's addresses or protocol.
For example, a packet sent to an L2TPv3 over IPv6 tunnel can be
delivered to an L2TPv2 over UDPv4 tunnel. This is worse than a simple
cross-talk: when delivering the packet to an L2TP over UDP tunnel, the
corresponding socket is UDP, where ->sk_backlog_rcv() is NULL. Calling
sk_receive_skb() will then crash the kernel by trying to execute this
callback.
And l2tp_tunnel_find() isn't even needed here. __l2tp_ip_bind_lookup()
properly checks the socket binding and connection settings. It was used
as a fallback mechanism for finding tunnels that didn't have their data
path registered yet. But it's not limited to this case and can be used
to replace l2tp_tunnel_find() in the general case.
Fix l2tp_ip6 in the same way.
Fixes:
|
||
|---|---|---|
| .. | ||
| Kconfig | ||
| Makefile | ||
| l2tp_core.c | ||
| l2tp_core.h | ||
| l2tp_debugfs.c | ||
| l2tp_eth.c | ||
| l2tp_ip.c | ||
| l2tp_ip6.c | ||
| l2tp_netlink.c | ||
| l2tp_ppp.c | ||